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MicroRNAs (miRNAs) broadly regulate normal biological functions of bone and the progression of fracture healing and osteoporosis. Recently, it has been reported that miR-1224-5p in fracture plasma is a potential therapy for osteogenesis. To investigate the roles of miR-1224-5p and the Rap1 signaling pathway in fracture healing and osteoporosis development and progression, we used BMMs, BMSCs, and skull osteoblast precursor cells for in vitro osteogenesis and osteoclastogenesis studies. Osteoblastogenesis and osteoclastogenesis were detected by ALP, ARS, and TRAP staining and bone slice resorption pit assays. The miR-1224-5p target gene was assessed by siRNA-mediated target gene knockdown and luciferase reporter assays. To explore the Rap1 pathway, we performed high-throughput sequencing, western blotting, RT-PCR, chromatin immunoprecipitation assays and immunohistochemical staining. In vivo, bone healing was judged by the cortical femoral defect, cranial bone defect and femoral fracture models. Progression of osteoporosis was evaluated by an ovariectomy model and an aged osteoporosis model. We discovered that the expression of miR-1224-5p was positively correlated with fracture healing progression. Moreover, in vitro, overexpression of miR-1224-5p slowed Rankl-induced osteoclast differentiation and promoted osteoblast differentiation via the Rap1-signaling pathway by targeting ADCY2. In addition, in vivo overexpression of miR-1224-5p significantly promoted fracture healing and ameliorated the progression of osteoporosis caused by estrogen deficiency or aging. Furthermore, knockdown of miRNA-1224-5p inhibited bone regeneration in mice and accelerated the progression of osteoporosis in elderly mice. Taken together, these results identify miR-1224-5p as a key bone osteogenic regulator, which may be a potential therapeutic target for osteoporosis and fracture nonunion.

A moderate inflammatory response at the early stages of fracture healing is necessary for callus formation. Over-active and continuous inflammation, however, impairs fracture healing and leads to excessive tissue damage. Adequate fracture healing could be promoted through suppression of local over-active immune cells in the fracture site. In the present study, we achieved an enriched concentration of PD-L1 from exosomes (Exos) of a genetically engineered Human Umbilical Vein Endothelial Cell (HUVECs), and demonstrated that exosomes overexpressing PD-L1 specifically bind to PD-1 on the T cell surface, suppressing the activation of T cells. Furthermore, exosomal PD-L1 induced Mesenchymal Stem Cells (MSCs) towards osteogenic differentiation when pre-cultured with T cells. Moreover, embedding of Exos into an injectable hydrogel allowed Exos delivery to the surrounding microenvironment in a time-released manner. Additionally, exosomal PD-L1, embedded in a hydrogel, markedly promoted callus formation and fracture healing in a murine model at the early over-active inflammation phase. Importantly, our results suggested that activation of T cells in the peripheral lymphatic tissues was inhibited after local administration of PD-L1-enriched Exos to the fracture sites, while T cells in distant immune organs such as the spleen were not affected. In summary, this study provides the first example of using PD-L1-enriched Exos for bone fracture repair, and highlights the potential of Hydrogel@Exos systems for bone fracture therapy through immune inhibitory effects.

The osteoblast/osteoclast and M1/M2 macrophage ratios play critical roles in delayed fracture healing. Robust osteoblast differentiation and M2 macrophage polarization can substantiality promote fracture repair; however, the combined effect of these strategies has not been previously studied. In this study, we constructed a cocktail therapy to simultaneously regulate the osteoblast/osteoclast and M1/M2 macrophage balance. The cocktail therapy composed of a natural polymer hyaluronic-acid-based hydrogel (HA hydrogel, which has a tissue-adhesive, injectable, self-healing, anti-inflammation profile), engineered endothelial cell-derived exosomes (EC-ExossupmiR-26a-5p/sup), and APY29, an IRE-1α inhibitor. This allowed for specific delivery of EC-ExossupmiR-26a-5p/supand APY29 for osteoblast/osteoclast and macrophage regulation, respectively. The results suggested that the cocktail therapy exerted pro-fracture repair effects with each of its components established as indispensable. The assessed cocktail therapy provides insight into synergistic strategies and is useful for developing more suitable pro-fracture repair therapy.

The immune system and skeletal system are closely linked. Macrophages are one of the most important immune cells for bone remodeling, playing a prohealing role mainly through M2 phenotype polarization. Baicalein (5,6,7-trihydroxyflavone, BCL) has been well documented to have a noticeable promotion effect on M2 macrophage polarization. However, due to the limitations in targeted delivery to macrophages and the toxic effect on other organs, BCL has rarely been used in the treatment of bone fractures. In this study, we developed mesoporous silica and Fe3O4 composite-targeted nanoparticles loaded with BCL (BCL@MMSNPs-SS-CD-NW), which could be magnetically delivered to the fracture site. This induced macrophage recruitment in a targeted manner, polarizing them toward the M2 phenotype, which was demonstrated to induce mesenchymal stem cells (MSCs) toward osteoblastic differentiation. The mesoporous silicon nanoparticles (MSNs) were prepared with surface sulfhydrylation and amination modification, and the mesoporous channels were blocked with β-cyclodextrin. The outer layer of the mesoporous silicon was added with an amantane-modified NW-targeting peptide to obtain the targeted nanosystem. After entering macrophages, BCL could be released from nanoparticles since the disulfide linker could be cleaved by intracellular glutathione (GSH), resulting in the removal of cyclodextrin (CD) gatekeeper, which is a key element in the pro-bone-remodeling functions such as anti-inflammation and induction of M2 macrophage polarization to facilitate osteogenic differentiation. This nanosystem passively accumulated in the fracture site, promoting osteogenic differentiation activities, highlighting a potent therapeutic benefit with high biosafety.

Hip fractures in the elderly account for more than half of osteoporotic fractures and represent a substantial economic and social burden. Novel coronavirus pneumonia (COVID-19), which began to spread in December 2019, has created challenges in the management of elderly hip fracture patients, not only by influencing the choice of operation and postoperative rehabilitation methods, but also by generating new risks for the medical staff. During this period, our infection and orthopedic treatment unit in the center of the epidemic area effectively treated 82 elderly patients with hip fracture, and no cross-infection occurred. Therefore, our experience in prevention and treatment is worth recommending to frontline anti-epidemic personnel.

Background Enhancing angiogenesis is critical for accelerating wound healing. Application of different types of exosomes (Exos) to promote angiogenesis represents a novel strategy for enhanced wound repair. Saliva is known to accelerate wound healing, but the underlying mechanisms remain unclear. Results Our results have demonstrated that saliva-derived exosomes (saliva-Exos) induce human umbilical vein endothelial cells (HUVEC) proliferation, migration, and angiogenesis in vitro, and promote cutaneous wound healing in vivo. Further experiments documented that Ubiquitin-conjugating enzyme E2O (UBE2O) is one of the main mRNAs of saliva-Exos, and activation of UBE2O has effects similar to those of saliva-Exos, both in vitro and in vivo. Mechanistically, UBE2O decreases the level of SMAD family member 6 (SMAD6), thereby activating bone morphogenetic protein 2 (BMP2), which, in turn, induces angiogenesis. Conclusions The present work suggests that administration of saliva-Exos and UBE2O represents a promising strategy for enhancing wound healing through promotion of angiogenesis.

Diabetic foot ulcers are a common complication of diabetes, and are usually incurable in the clinic. Exosomes (carriers that transfer endogenous molecules) from diabetic patients' blood have been demonstrated to suppress diabetic wound repair. In this study, we investigated the effects of circulating exosomal microRNA-15a-3p (miR-15a-3p) on diabetic wound repair. Exosomes were extracted from diabetic patients' blood, and were found to inhibit diabetic wound repair in vitro and in vivo. miR-15a-3p was upregulated in diabetic exosomes, and impaired wound healing. When miR-15a-3p was knocked down in diabetic exosomes, their negative effects were partially reversed both in vitro and in vivo. NADPH oxidase 5 (NOX5) was identified as a potential target of miR-15a-3p, and the inhibition of NOX5 reduced the release of reactive oxygen species, thereby impairing the functionality of human umbilical vein endothelial cells. In summary, inhibition of circulating exosomal miR-15a-3p accelerated diabetic wound repair by activating NOX5, providing a novel therapeutic target for diabetic foot ulcer therapy.

N6‐methyladenosine (m6A) modification has been reported in various diseases and implicated in increasing numbers of biological processes. However, previous studies have not focused on the role of m6A modification in fracture healing. Here, we demonstrated that m6A modifications are decreased during fracture healing and that methyltransferase‐like 3 (METTL3) is the main factor involved in the abnormal changes in m6A modifications. Down‐regulation of METTL3 promotes osteogenic processes both in vitro and in vivo, and this effect is recapitulated by the suppression of miR‐7212‐5p maturation. Further studies have shown that miR‐7212‐5p inhibits osteoblast differentiation in MC3T3‐E1 cells by targeting FGFR3. The present study demonstrated an important role of the METTL3/miR‐7212‐5p/FGFR3 axis and provided new insights on m6A modification in fracture healing.

Diabetic wounds remain a great challenge for clinicians due to the multiple bacterial infections and oxidative damage. Exosomes, as an appealing nanodrug delivery system, have been widely applied in the treatment of diabetic wounds. Endovascular cells are important component cells of the vascular wall. Herein, we investigated the effects of HUCMSCs and HUC-Exos (exosomes secreted by HUCMSCs) on diabetic wound healing. In this study, HUVECs were coincubated with HUCMSCs, and HUC-Exos were utilized for

BackgroundExtremity injuries, especially for bone fracture, predominate in warfare, and around one-third of military personnel sustain at least one kind of traumatic brain injury (TBI). The beneficial role of TBI in osteogenic differentiation and fracture healing was found in clinic, however, the underlying mechanism of this interesting finding is elusive. Exosome (Exos) is nanosized extracellular vesicles, and their regulatory role in bone remodeling have attracted accumulative attention.MethodsUltra-high speed gradient centrifugation was used to extract exosomes (Exos) both from fracture patients combined with TBI (TBI-Exos), and from isolated fracture patients (Ctr-Exos). Human mesenchymal stem cells (hMSCs) proliferation was checked by qRT-PCR, western blotting, ALP staining, alizarin red staining, and EdU (5-ethynyl-2’-deoxyuridine) assays. In addition, C57BL/6J mice were randomly divided into different groups according to the treatments, and the radiographic and histopathological results were analyzed to evaluate the effect of TBI-Exos on fracture healing. ResultsIn vitro, suppression of SMAD7 promoted osteogenic differentiation, whereas knock down of miR-21-5p in TBI-Exos deprived this bone-beneficial effect at a great extent. Similarly, our results confirmed that pre-injection of TBI-Exos leads to enhanced bone formation, whereas knock down of exosomal miR-21-5p was capable to markedly impair this bone-beneficial effect in vivo. ConclusionOur findings provide a potential mechanism of the beneficial role of TBI in fracture healing with a particular focus on the TBI-Exos, and suggest that the use of nanosized materials combined with miR-21-5p-mimics may be a promising therapeutic approach to enhance fracture healing in the future.

Osteoblast differentiation is a vital process for fracture healing, and exosomes are nanosized membrane vesicles that can deliver therapeutic drugs easily and safely. Macrophages participate in the regulation of various biological processes in vivo, and macrophage-derived exosomes (MD-Exos) have recently been a topic of increasing research interest. However, few study has explored the link between MD-Exos and osteoblast differentiation. Herein, we sought to identify miRNAs differentially expressed between M1 and M2 macrophage-derived exosomes, and to evaluate their roles in the context of osteoblast differentiation. We found that microRNA-5106 (miR-5106) was significantly overexpressed in M2 macrophage-derived exosomes (M2D-Exos), while its expression was decreased in M1 macrophage-derived exosomes (M1D-Exos), and we found that this exosomal miRNA can induce bone mesenchymal stem cell (BMSC) osteogenic differentiation via directly targeting the Salt-inducible kinase 2 and 3 (SIK2 and SIK3) genes. In addition, the local injection of both a miR-5106 agonist or M2D-Exos to fracture sites was sufficient to accelerate healing in vivo. Our study demonstrates that miR-5106 is highly enriched in M2D-Exos, and that it can be transferred to BMSCs wherein it targets SIK2 and SIK3 genes to promote osteoblast differentiation.

The treatment of diabetic wounds remains a major challenge in clinical practice, with chronic wounds characterized by multiple drug-resistant bacterial infections, angiopathy, and oxidative damage to the microenvironment. Herein, a novel in situ injectable HA@MnO2 /FGF-2/Exos hydrogel is introduced for improving diabetic wound healing. Through a simple local injection, this hydrogel is able to form a protective barrier covering the wound, providing rapid hemostasis and long-term antibacterial protection. The MnO2 /e-PL nanosheet is able to catalyze the excess H2 O2 produced in the wound, converting it to O2 , thus not only eliminating the harmful effects of H2 O2 but also providing O2 for wound healing. Moreover, the release of M2-derived Exosomes (M2 Exos) and FGF-2 growth factor stimulates angiogenesis and epithelization, respectively. These in vivo and in vitro results demonstrate accelerated healing of diabetic wounds with the use of the HA@MnO2 /FGF-2/Exos hydrogel, presenting a viable strategy for chronic diabetic wound repair.

Background: Macrophages are essential for fracture healing, acting mainly through remodeling of the extracellular matrix and promotion of angiogenesis. The role of macrophages in regulating osteogenic differentiation, particularly that of the M2 phenotype, is increasingly researched. Baicalein (BCL) had also been shown to have pro-fracture-healing effects.Results: In this study, we developed mesoporous silica and Fe3O4 composite-targeted nanoparticles loaded with BCL (BCL@MMSNPs-SS-CD-NW), that could be magnetically delivered to the fracture site. These induced macrophage recruitment in a targeted manner, polarizing them towards the M2 phenotype, and thereby inducing MSCs towards osteoblastic differentiation. The mesoporous silicon nanoparticles (MSNs) were prepared with surface sulfhydrylation and amination modification, and the mesoporous channels were blocked with β-cyclodextrin. The outer layer of the mesoporous silicon was added with an amantane-modified NW targeting peptide to obtain the targeted nano-system. After entering macrophages, BCL could be released from nanoparticles since the disulfide linker could be cleaved by intracellular glutathione (GSH) resulting in the removing of CD gatekeeper, which is a key element in the pro-bone-remodeling functions, such as anti-inflammation and induction of M2 macrophage polarization to facilitate osteogenic differentiation.Conclusions: This nano-system passively accumulated in the fracture site, promoting osteogenic differentiation activities, highlighting a potent therapeutic benefit with high biosafety.

Background We aimed to compare the intraoperative and early postoperative clinical outcomes of using an acromioclavicular joint hook plate (AJHP) versus a locking plate (LP) in the treatment of anterior sternoclavicular joint dislocation. Methods Seventeen patients with anterior sternoclavicular joint dislocation were retrospectively analyzed from May 2014 to September 2019. Six patients were surgically treated with an AJHP, and 11 were surgically treated with an LP. Five male and one female patients composed the AJHP group, and nine male and two female patients composed the LP group. The mean age of all patients was 49.5 years. Results Reduction and fixation were performed with AJHP or LP in all 17 patients. The mean operative blood loss, operative time, and length of incision in the AJHP group were significantly better than those in the LP group. Shoulder girdle movement of the AJHP group was significantly better than that of the LP group. Conclusions This study revealed that AJHP facilitated glenohumeral joint motion, reduced the risk of rupture of mediastinal structures, required a shorter incision, and had lesser blood loss and a shorter duration of operation compared with LP. However, some deficiencies require further improvement.

Currently, we found that double reverse traction repositor (DRTR) is a treatment with operation convenience and fast in our clinical work. However, the clinical efficacy and safety of DRTR in the reduction of unstable intertrochanteric fractures in elderly patients remain unknown. Therefore, the study aimed to compare the clinical efficacy and safety of DRTR and traction table (TT) in the reduction of unstable intertrochanteric fractures in elderly patients.From October 2018 to December 2020, the elderly patients with unstable intertrochanteric fractures were reviewed. 22 patients treated with TT and 20 patients treated with DRTR met the inclusion criteria of this study, and baseline clinical characteristics were recorded. The reduction time, operation time, incision length and intraoperative blood loss were reviewed. The safety outcome was assessed by postoperative complications, and the efficacy outcomes were evaluated by the fracture healing time based on the radiographs conducted at each follow-up (1, 3, 6, 12 months after surgery) and hip function (hip flexion, Harris Hip Score) at the final follow-up (12 months after surgery).There were no significant differences in terms of demographics and fracture characteristics of cases enrolled. In DRTR group, the average intraoperative reduction time [(34.8±7.6) min] and the average operation time [(87.1±12.2) min] were superior to those [(56.6±9.3); (123.1±15.0) min] in TT group (P0.0001). However, there were no statistical significance in terms of the average incision lengths [(6.4±0.9)Minimally invasive reduction with DRTR in unstable intertrochanteric fractures could effectively shorten the intraoperative reduction time and operation time in this study. Therefore, minimally invasive reduction with DRTR might be a good choice for intertrochanteric reduction of unstable intertrochanteric fractures.

The aim of this study was to evaluate the clinical application of double-reverse traction for minimally invasive reduction of complex tibial plateau fractures. A retrospective analysis was performed to identify all patients admitted to the Department of Orthopedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, from March 2017 to December 2019 with Schatzker type VI tibial plateau fractures. 12 patients were identified (7 men and 5 women) with an average age of 46.15 ± 13 (39-58) years old. All patients were treated with double-reverse traction and closed reduction. After the fracture was reduced, the bone plate was fixed by percutaneous minimally invasive implantation. Outcomes assessed in this study include operation time and intraoperative blood loss. Imaging was performed during the postoperative follow-up, and functional recovery was evaluated at the final follow-up according to the Hospital for Special Surgery (HSS) score and the International Knee Joint Literature Committee (IKDC) functional score. Patients were followed up for 12.54 ± 1.5 (8-15) months. The average operation time was 63.63 ± 21 (35-120) minutes, and the average intraoperative blood loss was 105.45 ± 21 (60-200) mL. The Rasmussen imaging score was either excellent or good in all cases. The knee joint HSS score was 86.15 ± 6 (79-90) points, and the IKDC score was 80.01 ± 11 (75-90) points. No complications, such as wound infection, incision disunion, loosening of internal fixation, and internal fixation failure, occurred. In the treatment of Schatzker VI type complex tibial plateau fracture, the dual-reverse traction minimally invasive technique has the advantages of safety and effectiveness, less soft tissue injury, and allowing early joint movement, which is worthy of clinical promotion.

Deep venous thrombosis (DVT) is a common complication in patients with lower extremity fractures, causing delays in recovery short-term and possible impacts on quality of life long-term. Early prediction and prevention of thrombosis can effectively reduce patient pain while improving outcomes. Although research on the risk factors for thrombosis is prevalent, there is a stark lack of clinical predictive models for DVT occurrence specifically in patients with lower limb fractures. In this study, we aim to propose a new thrombus prediction model for lower extremity fracture patients. Data from 3300 patients with lower limb fractures were collected from Wuhan Union Hospital and Hebei Third Hospital, China. Patients who met our inclusion criteria were divided into a thrombosis and a nonthrombosis group. A multivariate logistic regression analysis was carried out to identify predictors with obvious effects, and the corresponding formulas were used to establish the model. Model performance was evaluated using a discrimination and correction curve. 2662 patients were included in the regression analysis, with 1666 in the thrombosis group and 996 in the nonthrombosis group. Predictive factors included age, Body Mass Index (BMI), fracture-fixation types, energy of impact at the time of injury, blood transfusion during hospitalization, and use of anticoagulant drugs. The discriminative ability of the model was verified using the C-statistic (0.676). For the convenience of clinical use, a score table and nomogram were compiled. Data from two centers were used to establish a novel thrombus prediction model specific for patients with lower limb fractures, with verified predictive ability.

The angiotensin-converting enzyme 2 (ACE2) receptor has been identified as the cell entry point for SARS-CoV-2. Although ACE2 receptors are present in the bone marrow, the effects of SARS-CoV-2 on the biological activity of bone tissue have not yet been elucidated. In the present study we sought to investigate the impact of SARS-CoV-2 on osteoblastic activity in the context of fracture healing. MicroRNA-4485 (miR-4485), which we found to be upregulated in COVID-19 patients, negatively regulates osteogenic differentiation. We demonstrate this effect both in vitro and in vivo. Moreover, we identified the toll-like receptor 4 (TLR-4) as the potential target gene of miR-4485, and showed that reduction of TLR-4 induced by miR-4485 suppresses osteoblastic differentiation in vitro. Taken together, our findings highlight that up-regulation of miR-4485 is responsible for the suppression of osteogenic differentiation in COVID-19 patients, and TLR-4 is the potential target through which miR-4485 acts, providing a promising target for pro-fracture-healing and anti-osteoporosis therapy in COVID-19 patients.

Mesenchymal stem cells (MSCs) critically contribute to bone formation, and proper induction of osteogenic differentiation can lead to an increase in bone mass. In the present study, we reported that an increased miR-194-5p level in plasma is inversely related to the degree of bone formation in osteoporosis patients. We also noted that increased miR-194-5p in the MSCs of ovariectomized (OVX) mice and agomiR-194-5p manipulation of miR-194-5p significantly suppressed bone formation, both in aged and OVX mice. Furthermore, our in vitro study showed that overexpression of miR-194-5p suppresses osteogenic differentiation, as evidenced by the decreased bone formation marker genes and matrix mineralization. The luciferase assay indicated that Wnt family member 5a (Wnt5a) is a target gene of miR-194-5p that positively regulates osteogenic differentiation. Collectively, these data indicated that miR-194-5p inhibition may be a potential strategy for osteoporosis prevention., Graphical Abstract, miRNAs have been reported to be closely related with osteoporosis progression. In this study, Mi et al. identified that the miR-194-5p level is highly increased in the plasma of osteoporosis patients, which suppresses bone formation both in vitro and in vivo. These findings suggested that miR-194-5p inhibition may be a potential strategy for osteoporosis prevention.

Osteomyelitis, an infection of the bone and bone marrow, imposes a heavy burden on public health care systems owing to its progressive bone destruction and sequestration. Human bone mesenchymal stem cells (hBMSCs) play a key role in the process of bone formation, and mounting evidence has confirmed that long noncoding RNAs (lncRNAs) are involved in hBMSC osteogenic differentiation. Nevertheless, the exact function and molecular mechanism of lncRNAs in osteogenic differentiation during osteomyelitis development remain to be explored. In this study, hBMSCs were treated with staphylococcal protein A (SpA) during osteogenic differentiation induction to mimic osteomyelitis in vitro. The results of lncRNA microarray analysis revealed that FAM83H-AS1 presented the lowest expression among the significantly downregulated lncRNAs. Functionally, ectopic expression of FAM83H-AS1 contributed to osteogenic differentiation of SpA-induced hBMSCs. Additionally, our findings revealed that FAM83H-AS1 negatively regulated microRNA 541-3p (miR-541-3p), and WNT3A was validated as a target gene of miR-541-3p. Mechanically, FAM83H-AS1 elevated WNT3A expression by competitively binding with miR-541-3p. Lastly, it was demonstrated that FAM83H-AS1/miR-541-3p/WNT3A ameliorated SpA-mediated inhibition of the osteogenic differentiation of hBMSCs, which provided a novel therapeutic strategy for patients with osteomyelitis.

Additional file 1: Figure 1. (A) BMDM, (B) M1 macrophage, and (C) M2 macrophage were identified by flow cytometry. Figure 2. The biocompatibility of M1D- and M2D- Exos was tested by CCK-8 assay. Figure 3. In the control group, the appearance of Cy3 red fluorescence on BMSCs was examined after co-culture with M1/M2 macrophages treated with Cy3 dye (without miR-26a-5p mimic) for 12 hours. Figure 4. Relative intensity of western blotting analysis.

Enhancing angiogenesis is critical for accelerating wound healing. Application of different types of exosomes (Exos) to promote angiogenesis represents a novel strategy for enhanced wound repair. Saliva is known to accelerate wound healing, but the underlying mechanisms remain unclear. In the present study, Exos were isolated from saliva, and their effect on angiogenesis was explored in vitro and in vivo. Our results have demonstrated that saliva-derived exosomes (saliva-Exos) induce HUVEC proliferation, migration, and angiogenesis in vitro, and promote cutaneous wound healing in vivo. Further experiments documented that Ubiquitin-conjugating enzyme E2O (UBE2O) is one of the main components of saliva-Exos, and activation of UBE2O has effects similar to those of saliva-Exos, both in vitro and in vivo. Mechanistically, UBE2O decreases the level of SMAD6, thereby activating BMP2, which, in turn, induces angiogenesis. The present work suggests that administration of saliva-Exos and UBE2O represents a promising strategy for enhancing wound healing through promotion of angiogenesis.

Background: The clinical characteristics and outcomes of surgical treatment of patients with COVID-19 remain unclear This study aimed to determine whether surg

Although the immune system is well recognized as a key player in fracture repair, the exact mechanisms, particularly the role of regulatory T-cells (Tregs), have not yet been established. Our increased understanding of the Tregs and exosomes involved in organ repair creates opportunity of application of Tregs derived Exosomes (TregD-Exos) in the modulation of fracture repair. In the present study, we report that TregD-Exos containing miR-142-3p can be shuttled into bone mesenchymal stem cells (BMSCs) and Human umbilical vein endothelial cells (HUVECs) promoting osteogenesis and angiogenesis. Overexpression of miR-142-3p remarkedly promoted BMSC osteoblastic differentiation, and enhanced HUVEC function, including proliferation, migration and angiogenesis. Furthermore, TGFBR1/SMAD2 was shown to be involved in the TregD-Exos’ promotive effect on bone healing. Moreover, both TregD-Exos and miR-142-3p administration restored bone repair in vivo. Taken together, our results indicate that TregD-Exos containing miR-142-3p can be transferred to BMSCs and HUVECs with robust effects on osteogenesis and angiogenesis. These findings shed a new light for the use of Tregs in facilitating bone repair, suggesting that both TregD-Exos and miR-142-3p are promising effective therapeutic agents for bone remodeling.

Fracture healing is a complex process involving various cell types, cytokines, and mRNAs. Here, we report the roles of the circRNA AFF4/miR-7223-5p/PIK3R1 axis during fracture healing. We found that increased expression of PIK3R1 during fracture healing is directly associated with augmented proliferation and decreased apoptosis of MC3T3-E1 cells. Furthermore, miR-7223-5p targeted PI3KR1 and inhibited MC3T3-E1 proliferation while promoting apoptosis. CircRNA AFF4 acted as a sponge of miR-7223-5p, thereby promoting MC3T3-E1 cell proliferation and inhibiting apoptosis. Local injection of circRNA AFF4 into femoral fracture sites promoted fracture healing in vivo while the injection of miR-7223-5p delayed healing. These findings suggest that CircRNA AFF4 promotes fracture healing by targeting the miR-7223-5p/PIK3R1 axis, and suggests miR-7223-5p, CircRNA AFF4, and the miR-7223-5p/PIK3R1 axis are potential therapeutic targets for improving fracture healing.

A number of recent studies have highlighted the causes of bone nonunion (BN), however, the rate of BN incidence continues to rise and available therapeutic options to treat this condition remain limited. Thus, to prevent disease progression and improve patient prognosis, it is vital that BN, or the risk thereof, be accurately identified in a timely manner. In the present study, bioinformatics analyses were used to screen for the differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMs) between patients with BN and those with bone union, using data from the Gene Expression Omnibus database. Furthermore, clinical samples were collected and analyzed by reverse transcription‑quantitative PCR and western blotting. In vitro and in vivo experiments were carried out to confirm the relationship between BN and the DEGs of interest, in addition to being used to explore the underlying molecular mechanism of BN. Functional enrichment analysis of the downregulated DEGs revealed them to be enriched for genes associated with 'ECM‑receptor interactions', 'focal adhesion', 'and the calcium signaling pathway'. When comparing DEM target genes with these DEGs, nine DEGs were identified as putative DEM targets, where hsa‑microRNA (miR)‑1225‑5p‑CCNL2, hsa‑miR‑339‑5p‑PRCP, and hsa‑miR‑193a‑3p‑mitogen‑activated protein kinase 10 (MAPK10) were the only three pairs which were associated with decreased gene expression levels. Furthermore, hsa‑miR‑193a‑3p was demonstrated to induce BN by targeting MAPK10. Collectively, the results of the present study suggest that hsa‑miR‑193a‑3p may be a viable biomarker of BN.

Hydrogels could be promising wound healing dressings that maintain a moist environment in the wound site and accelerate wound healing. However, the lack of antibacterial effect, suitable mechanical property and adhesiveness limits their applications. Here, we designed a quaternized chitosan-Matrigel-polyacrylamide (QCS-M-PAM) hydrogel with multi-functions. The morphology, swelling ratio, mechanical test, antimicrobial property, hemostatic performance and biocompatibility of the hybrid hydrogel were investigated in vitro and vivo. The hybrid hydrogel showed a three-dimensional (3D) microporous structure, high swelling ratio, excellent stretchable and compressive property, similar modulus to human skin, good adhesiveness, and low cytotoxicity. The results of histology and molecular testing in vivo demonstrated that the hybrid hydrogel could significantly enhance wound healing, collagen deposition, and induce skin adnexal regeneration by upregulating anti-inflammatory factors, and downregulating proinflammatory factors. Together, the present antibacterial hydrogels with hemostatic and adhesive properties are considered to have promising potential used as wound dressings for full-thickness skin defect.

Patients who sustain a traumatic brain injury (TBI) are known to have a significantly quicker fracture healing time than patients with isolated fractures, but the underlying mechanism has yet to be identified. In this study, we found that the upregulation of miRNA-26a-5p induced by TBI correlated with a decrease in phosphatase and tensin homolog (PTEN) in callus formation. In vitro, overexpressing miRNA-26a-5p inhibited PTEN expression and accelerated osteoblast differentiation, whereas silencing of miRNA-26a-5p inhibited osteoblast activity. Reduction of PTEN facilitated osteoblast differentiation via the PI3K/AKT signaling pathway. Through luciferase assays, we found evidence that PTEN is a miRNA-26a-5p target gene that negatively regulates the differentiation of osteoblasts. Moreover, the present study confirmed that preinjection of agomiR-26a-5p leads to increased bone formation. Collectively, these results indicate that miRNA-26a-5p overexpression may be a key factor governing the improved fracture healing observed in TBI patients after the downregulation of PTEN and PI3K/AKT signaling. Upregulation of miRNA-26a-5p may therefore be a promising therapeutic strategy for promoting fracture healing. Keywords: traumatic brain injury, fracture, miRNA, PTEN